I tested with rhel7 and ed25519 works with this, so it should work with rhel8 too. Haven’t a SUSE installation to check/test, but expect that would be fine also.
Check that the key is pasted correctly under your user preferences, and then attempt something like this:
ssh -vvv git@yourserver
then we can see from the debug output from ssh where the problem seems to be. You can also do:
ssh -T git@yourserver
when I do this, I get this response:
ian@elise:~$ ssh -T firstname.lastname@example.org
Welcome to GitLab, @iwalker!
obviously using the public gitlab server in my example, but change this for yours. We’ll then see from the debug output.
When copying the key, the easiest way is do:
and copy the entire line and paste this in your profile. I expect you probably did that anyway, but just wanted to be sure. It should look similar to below:
ssh-ed25519 AAAAsomekeyvaluehere user@hostname